Pneumatic motor

ABSTRACT

A pneumatic motor includes a cylinder and a rotor disposed in the cylinder. The rotor includes an axle, and main and secondary blades are slidably received in a plurality of main and secondary sliding slots formed on the axle. The secondary blades touch an inner wall of the cylinder to promote torque output when located at angles equal to or smaller than a specific angle from an inlet of the cylinder. On the contrary, the secondary blades are away from the inner wall of the cylinder to reduce friction between the rotor and the cylinder when located at angles larger than the specific angle from the inlet. Thus, revolution speed of the rotor is retained in a tolerant range, and torque output is promoted significantly.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a pneumatic motor, more particularly to a rotor of a pneumatic motor.

2. Description of the Prior Art

A pneumatic motor is driven by compressed air to provide torque output to drive other tools to rotate further. A conventional pneumatic motor usually has adjustment mechanism to increase power output. For example, a pneumatic motor disclosed in patent TW 1259865 has two sets of inlet and outlet, and the motor also includes a control valve assembly to alternatively open or close the inlet and the outlet. Thus, power stoke of compressed air in the motor is increased, and larger torque output is provided.

However, conventional pneumatic motors don't have sufficient stability of power output. Please refer to a pneumatic motor disclosed in patent TW M388576, the rotor disposes only three blades. When the rotor is driven to rotate by compressed air, entering and releasing of compressed air result that torque the rotor acquires varies to reduce stability, and vibration of the motor is increased. Thus, another conventional pneumatic motor has six blades to provide stabler and larger torque output.

When more blades are employed in a pneumatic motor, more slots should be formed on the rotor, and strength of the rotor is thereby decreased. Hence, number of blades in a pneumatic motor is limited, and applying more blades on a pneumatic motor for providing stabler torque output becomes unworkable in practice.

Moreover, applying more blades on a pneumatic motor can help increase contact with compressed air to provide larger torque output theoretically. However, more blades results more friction with the inner wall of cylinder when the axle rotates. Thus, torque output is not promoted distinctly, and rpm of the rotor is decreased under a tolerant minimum of 10%.

The present invention is, therefore, arisen to obviate or at least mitigate the above mentioned disadvantages.

SUMMARY OF THE INVENTION

The main object of the present invention is to provide a pneumatic motor which is able to provide stabler and larger torque output.

The other object of the present invention is to provide a pneumatic motor with more blades which retains enough strength of rotor and is able to provide larger torque output.

To achieve the above and other objects, a pneumatic motor of the present invention includes a cylinder, a rotor, and a limitation mechanism.

The cylinder encloses a receiving room, an inlet, and an outlet, wherein the inlet and the outlet communicate with the receiving room. The cylinder has an inner wall defined on a circumference of the receiving room.

The rotor includes an axle and a plurality of main blades. The axle defines an axial direction and a radial direction. The axle is rotatably disposed in the receiving room deviating from a center of the receiving room. The axle has an outer surface. The axle forms a plurality of main sliding slots which are radially recessed, and the main sliding slots are annularly arranged around the outer surface of the axle. Each main blade is disposed in one of the main sliding slot and is able to slide radially. Thus, when the axle rotates, each main blade is able to rotate simultaneously and touch the inner wall of the cylinder. The axle and the main blades partition the receiving room into a plurality of air chamber to enable compressed air to drive the rotor to rotate and to be released from the outlet.

Furthermore, the rotor also includes a plurality of secondary blades, and the axle forms a plurality of secondary sliding slots which are radially recessed. The secondary sliding slots are annularly arranged around the outer surface. Each secondary sliding slot has a smaller depth than a depth of each main sliding slot, and each secondary sliding slot has a smaller length than a length of each main sliding slot. Each secondary blade is slidably disposed in one of the secondary sliding slot, and the limitation mechanism is able to prevent the secondary blade from leaving the secondary sliding slot. When the axle rotates, each secondary blade rotates simultaneously. Each secondary blade is able to slide radially and to partially protrude outside of the outer surface. Thus, each secondary blade is able to touch the inner wall when located at angles equal to or smaller than a specific angle from the inlet, and each secondary blade is away from the inner wall when located at angles larger than a specific angle from the inlet.

Therefore, the secondary blades help promote torque output, and friction between the rotor and the cylinder is decreased due to the secondary blades which are away from the inner wall of the cylinder when the secondary blades are located at angles larger than the specific angle from the inlet. Thus, efficiency is promoted, and the revolution speed of the rotor is still in a tolerant range.

The present invention will become more obvious from the following description when taken in connection with the accompanying drawings, which show, for purpose of illustrations only, the preferred embodiment(s) in accordance with the present invention.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a stereogram of the present invention;

FIG. 2 is a breakdown drawing of the present invention;

FIG. 3 is an illustration of the present invention;

FIG. 4 is an illustration when the axle rotates of the present invention;

FIG. 5 is a breakdown drawing showing a second embodiment of the present invention;

FIG. 6 is an illustration showing a second embodiment of the present invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

Please refer to FIG. 1 and FIG. 2 for a major embodiment of the present invention. The pneumatic motor of the present invention is adapted for being installed in pneumatic tools and for being driven by compressed air. The pneumatic motor of the present embodiment includes a cylinder 1, a rotor 2, and a limitation mechanism.

The cylinder 1 encloses a receiving room 11, an inlet 12, and an outlet 12, wherein the inlet 12 and the outlet 13 communicate with the receiving room 11. The cylinder 1 has an inner wall defined on a circumference of the receiving room 11. Compressed air is able to enter the receiving room 11 via the inlet 12 and then to be discharged via the outlet 13. In other possible embodiment, the cylinder 1 can form a plurality of inlets and outlets, and path of compressed air is able to be changed by a valve. Thus, operating direction of the motor can be changed.

The rotor 2 includes an axle 21 and a plurality of main blades 22. An axial direction and a radial direction are defined by the axle 21. The axle 21 is rotatably disposed in the receiving room 11 deviating from a center of the receiving room 11. In other word, a center of the axle 21 is separated from the center of the receiving room 11. The axle 21 has an outer surface 211 and forms a plurality of main sliding slots 212 which are recessed radially. The main sliding slots 212 are annularly arranged around the outer surface 211. Each main blade 22 is disposed in one of the main sliding slot 212 and is able to slide radially. Thereby, when the axle 21 rotates, each main blade 22 is able to rotate simultaneously and to touch the inner wall radially. The axle 21 and the main blades 22 partition the receiving room 11 into a plurality of air chambers. Thus, due to the air chambers, compressed air is able to enter the receiving room 11 via the inlet 12 to drive the rotor 2 to rotate, and compressed air is able to be discharged via the outlet 13.

The rotor 2 further includes a plurality of secondary blades 23 which are shorter than the main blades. The axle 21 forms a plurality of secondary sliding slots 213 which are radially recessed. The secondary sliding slots 213 are annularly arranged around the outer surface 211, and a depth of each secondary sliding slot 213 is smaller than a depth of each main sliding slot 212. More preferably, a number of the secondary sliding slots 213 is equal to a number of the main sliding slots 212. Besides, the secondary sliding slots 213 are arranged alternatively. In other words, each secondary sliding slot 213 is located between two of the main sliding slot 212. Each secondary blade 23 is slidably disposed in one of the secondary sliding slots 213. Each secondary blade 23 is able to slide radially and to partially protrude outside of the outer surface 211.

The limitation mechanism is adapted for retain each secondary blade 23 to corresponding secondary sliding slot 213 when the axle 21 rotates. Also, due to the limitation mechanism, each secondary blade 23 is able to touch the inner wall of the cylinder when located at angles equal to or smaller than a specific angle from the inlet, as shown in FIGS. 3 and 4. On the contrary, each secondary blade 23 doesn't touch and is away from the inner wall of the cylinder when located at angles larger than the specific angle, so that friction between the rotor and the inner wall of the cylinder is reduced to retain a revolution speed (rpm) in a tolerant range. In the major embodiment of the present invention, the specific angle is equal to or smaller than 160 degrees. More preferably, the specific angle is 98 degrees.

Furthermore, the limitation mechanism includes a plurality of ribs 31 and a plurality of limitation slots 32. The ribs 31 are formed on two opposite sides of each secondary blade 23 respectively, and the limitation slots 32 are formed on two opposite sides of each secondary sliding slot 213 respectively. The ribs 31 are slidably disposed in the limitation slots 32. As such, the ribs 31 and the secondary blades 23 are restricted in the limitation slots 32 and the secondary sliding slots 213. More preferably, the ribs 31, the secondary blades 23, the limitation slots 32, and the secondary sliding slots 213 are equal in axial length.

Please refer to FIGS. 3 and 4, when compressed air enters the receiving room from the inlet 12 for driving the rotor, compressed air is filled in an air chamber between the main blades 22 and 22′ first. Due to rotation of the axle 21, the secondary blade 23 protrudes outside of the outer surface of the axle 21 and abuts against the inner wall of the cylinder. Thus, the secondary blade 23 partitions the air chamber into two smaller secondary air chambers for filled with air. When the axle 21 rotates, a radial distance between the axle 21 and the inner wall increases. Due to the limitation mechanism, the secondary blade 23 leaves the inner wall, and the secondary air chambers are united to a single air chamber. Thereby, the secondary blades are able to partition the receiving room into a plurality of secondary air chambers for filled with air, so that the axle 21 is able to rotate in a more continuous manner to provide stabler output.

Moreover, the secondary blades 23 are able to abut against the inner wall of the cylinder when located at angles equal to or smaller than the specific angle, so that torque output can be promoted. Besides, the secondary blades 23 leave the inner wall of the cylinder when located at angles larger than the specific angle, so that friction between the rotor and the inner wall of the cylinder is reduced. Thus, under the premise that the revolution speed which the rotor loses is under 10%, torque output of the cylinder is promoted significantly.

On the other hand, the applicant had some efficiency tests by applying the present invention to pneumatic tools which are manufactured by Hyphone Machine Industry CO., LTD. The following tables show models of tools and the acquired data.

HY-2360 Conventional The present Rate of (without invention (with promoted secondary blades) secondary blades) efficiency Revolution speed 7281 6603 −9% Torque 320 340  6% Reverse 7584 6909 −9% revolution speed Reverse torque 330 350  6%

HY-1742 Conventional The present Rate (without invention (with of promoted secondary blades) secondary blades) efficiency Revolution 14,389 14,309 −1% speed Horsepower 0.87 0.98~1.08 Average 0.87 1.03 18% horsepower

The previous tables show test data of an air impact wrench model HY-2360 and a grinder model HY-1742 which are manufactured by Hyphone Machine Industry CO., LTD. Referring to the data, revolution speed of the present invention is lower than a conventional pneumatic motor but still in a tolerant range of 10%. However, larger torque output is provided. The revolution speed is probably lowered by mass of the rotor or moment of inertia, and the revolution speed is able to be promoted by reducing mass of elements of the rotor or moment of inertia of the rotor. Thus, referring to the test data, the pneumatic motor is able to provide larger output absolutely.

In addition, the secondary sliding slots may results that too many sliding slots should be formed on the axle, so that strength of structure of the axle may be reduced. Thus, bottoms of the main sliding slots and the secondary sliding slots may collapse. To prevent the previous situation, the secondary sliding slots of the present invention have smaller depths than depths of the main sliding slots, so that bottoms of main sliding slots and secondary sliding slots can dodge from each other. Strength of structure of the axle is thereby retained.

Please refer to FIGS. 5 and 6 for another embodiment of the present invention. The limitation mechanism can be designed as another form to retain the secondary blades in the secondary sliding slots. More specifically, referring to FIG. 5, the limitation mechanism includes a plurality of abutting slots 41, a plurality of tenons 42, and a plurality of positioning slots 43. The abutting slots 41 are formed on two opposite sides of each secondary sliding slot 213. The tenons 42 are disposed in the abutting slots 41, so each tenon 42 is fixedly received in one of the secondary sliding slot 213. More preferably, each of the two sides of the secondary blade 23 has a tenon 42, so a number of the tenons 42 is twice than a number of the secondary blades 23. The positioning slots 43 are formed on the secondary blades 23. Each tenon 42 is slidably received in one of the positioning slots 43 to block the secondary blade 23 and to prevent the secondary blade 23 from leaving the secondary sliding slots 213.

In conclusion, the shorter secondary blades are able to partition the receiving room into a plurality of secondary air chambers for filled with compressed air continuously, so that the axle can be driven uniformly. In addition, the secondary blades help contribute the torque output. Also, the secondary blades don't touch the inner wall of the cylinder when located at angles larger than the specific angle from the inlet, so that the friction between the rotor and the cylinder is reduced. 

What is claimed is:
 1. A pneumatic motor, comprising: a cylinder, enclosing a receiving room, an inlet, and a outlet, the inlet and the outlet communicating with the receiving room respectively, the cylinder having an inner wall defined on a circumference of the receiving room; and a rotor, including an axle, a plurality of main blades, and a plurality of secondary blades which are shorter than the main blades, the axle defining an axial direction and a radial direction, the axle being rotatably disposed in the receiving room deviating from a center of the receiving room, the axle has an outer surface, the axle forming a plurality of main sliding slots and secondary sliding slots which are recessed radially, the main and the secondary sliding slots being annularly arranged around the outer surface, each main blade being disposed in one of the main sliding slot and being able to slide radially therein, each secondary blade being disposed in one of the secondary sliding slot and being able to slide radially therein, each main blade being able to rotate and to abut against the inner wall when the axle rotates, secondary blades which are located at angles equal to or smaller than a specific angle from the inlet being able to touch the inner wall when the axle rotate; wherein the specific angle is equal to or smaller than 160 degrees.
 2. The pneumatic motor of claim 1, further including a limitation mechanism, the limitation mechanism enabling each secondary blade to slide radially to protrude outside of the outer surface of the axle but not to leave the secondary sliding slot when the axle rotates.
 3. The pneumatic motor of claim 1, wherein the axle and the main blades partition the receiving room into a plurality of air chamber, each secondary sliding slot has a smaller depth than a depth of each main sliding slot, a number of the secondary sliding slots is equal to a number of the main sliding slots, the main and the secondary sliding slots are arranged alternately.
 4. The pneumatic motor of claim 2, wherein the limitation mechanism includes a plurality of ribs and limitation slots, the ribs protrude from two opposite sides of each secondary blade, the limitation slots are formed at two opposite sides of each secondary sliding slot, the ribs are slidably disposed in the limitation slots respectively to prevent the ribs and the secondary blades from leaving the limitation slots and the secondary sliding slots.
 5. The pneumatic motor of claim 4, wherein the ribs, the secondary blades, the limitation slots, and the secondary sliding slots has a same axial length.
 6. The pneumatic motor of claim 2, wherein the limitation mechanism includes a plurality of abutting slots, a plurality of tenons, and a plurality of positioning slots, the abutting slots are formed on two opposite sides of each secondary sliding slots respectively, each tenon is disposed in one of the abutting slot and are fixed in one of the secondary sliding slot, the positioning slots are formed on the secondary blades, each tenon is slidably received in one of the positioning slot to abut against the secondary blades.
 7. The pneumatic motor of claim 6, wherein a number of the tenons is twice than a number of the secondary blades, each of the two opposite sides of each secondary blade disposes a tenon. 